Depending on how old the unit is, it will either have a replacement fuse or reset breaker.
Older model units will have a replacement fuse located on the back of the unit near the power cable. You'll need to remove the (push in - twist off) cap, in order to get to it and check to see if it's blown.
Newer models have a reset breaker and are also located on the back near the power cable, labeled 10A. You'll need to simply press on the breaker and that should do the trick.